Acquired dermal melanocytosis: a case with conjunctival and gingival pigmentation.

A 28-year-old Japanese woman was referred to us because of widespread bilateral blue-gray and brown pigmentation on her face. Pigmentation was apparant on both sclerae, the alae of the nose, the lower lip and the gingiva; and it was also evident on her extremities. A biopsy specimen revealed melanin-containing cells and numerous mononulear cells in the upper dermis, particularly, near the small vessels. The melanin-containing cells immunoreacted with S100-specific antibodies but did not react with CD68-specific antibodies, these observations indicated that they were melanocytes. A diagnosis was made of acquired dermal melanocytosis (ADM), even though ADM is very rarely associated with conjunctival and mucosal involvement. Dermal melanocytes and large numbers of mononuclear cells adjacent to small vessels in the upper dermis have not previously been reported in ADM. Such melanocytes might play an important role in protecting blood cells from ultraviolet light. The presence of mononuclear cells close to melanocytes suggests that an inflammatory reaction might have initiated the activation of these dermal melanocytes.